> From: Dan Carpenter > Sent: Thursday, July 23, 2015 18:25 > On Thu, Jul 23, 2015 at 01:10:57PM +0300, Dan Carpenter wrote: > > In this specific case, writing it as "if (ret != 0)" caused the bug. If > > we had written it as "if (ret) return ret;" then there are no zeroes so > > wouldn't have been any temptation to return the zero instead of the ret. > > I did a search to see if returning the zero instead of the ret was a > common mistake and it seems like it might be. I did: > > grep 'if (ret != 0)' drivers/ -r -A1 -n | grep "return 0;" | perl -ne 's/.c-(\d+)-/.c:$1/; > print' > > drivers/gpu/drm/nouveau/nouveau_display.c:111 return 0; > drivers/regulator/wm8400-regulator.c:47 return 0; > drivers/platform/x86/dell-laptop.c:859 return 0; > drivers/media/dvb-frontends/dibx000_common.c:213 return 0; > drivers/media/dvb-frontends/dibx000_common.c:217 return 0; > drivers/media/dvb-frontends/dibx000_common.c:235 return 0; > drivers/media/dvb-frontends/dibx000_common.c:239 return 0; > drivers/hv/channel.c:898 return 0; > drivers/hv/channel.c:944 return 0; > > A bunch of those look suspicious but I don't know the subsystems well > enough to be sure. Can you check the last two? > > dan carpenter Thanks, Dan! After I checked the code, I think there is no issue for the last two: in the case of "if (ret != 0) return 0;", the output parameter buffer_actual_len is zero and it is explicitly checked by the callers. This may seem not natural and I think we can improve it in future. BTW, at the end of vmbus_recvpacket(), the "return 0;" should be "return ret;", but since the output parameter buffer_actual_len is checked by the callers, I think it's OK for now. Thanks, -- Dexuan _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
